Abstract:

A method and a device for estimating on an aircraft at least one wind
characteristic.
The device (1) comprises means (7) for determining a corrective term being
representative of an apparent wind created upon a rotation of the
aircraft and means (4) for determining the wind characteristic taking
into account such a corrective term.

Claims:

1. A method for automatically estimating aboard an aircraft (AC) at least
one wind characteristic existing outside said aircraft (AC), such a
method wherein, upon said aircraft (AC) flying, the following automated
operations are performed:a) a first piece of speed information is
received relating to the speed of the aircraft (AC) in a terrestrial
reference system, being expressed in a first point (G) of the aircraft
(AC);b) a second piece of speed information ({right arrow over (Vair)})
is received relating to the speed of the aircraft (AC) in the air, being
expressed in a second point (A) of the aircraft; andc) from at least said
first and second speed information, said wind characteristic is
determined in said terrestrial reference system, such a wind
characteristic being determined taking into account a corrective term
being representative of an apparent wind,wherein said corrective term TC
is calculated using the following expression:TC={right arrow over
(Ω)} {right arrow over (GA)}wherein: represents the vector
product;{right arrow over (Ω)} represents the rotation rate of the
aircraft (AC) in an inertial reference system;G represents a reference
point of the aircraft (AC), corresponding to said first point; andA
represents the position on the aircraft (AC) of at least one anemometric
probe, the measurements thereof being used for determining said second
piece of speed information, such a position A corresponding to said
second point.

2. A method according to claim 1,wherein in step c), there is calculated,
as a wind characteristic, a speed vector {right arrow over (Vv)} of said
wind, using the following expression:{right arrow over (Vv)}={right arrow
over (Vgs)}-{right arrow over (Vair)}+{right arrow over (Ω)} {right
arrow over (GA)}wherein:{right arrow over (Vgs)} represents said first
piece of speed information;{right arrow over (Vair)} represents said
second piece of speed information; represents the vector product;{right
arrow over (Ω)} represents the rotation rate of the aircraft (AC)
in an inertial reference system;G represents a reference point of the
aircraft (AC), corresponding to said first point; andA represents the
position on the aircraft (AC) of at least one anemometric probe, the
measurements thereof being used for determining said second piece of
speed information, such a position A corresponding to said second point.

3. A method for automatically generating aboard an aircraft (AC) at least
one wind characteristic existing outside said aircraft (AC),wherein, upon
said aircraft (AC) flying, the following automated operations are
performed:a) a first piece of speed information is determined on the
aircraft (AC);b) a second piece of speed information is determined on the
aircraft (AC); andc) from said first and second speed information, said
wind characteristic is determined, implementing the method according to
claim 1.

4. A device for automatically estimating aboard an aircraft (AC) at least
one wind characteristic existing outside said aircraft (AC), said device
(1) being aboard the aircraft (AC) and comprising:first means (2) for
receiving a first piece of speed information relating to the speed of the
aircraft (AC) in a terrestrial reference system, being expressed in a
first point (G) of the aircraft (AC);second means (3) for receiving a
second piece of speed information ({right arrow over (Vair)}) relating to
the speed of the aircraft (AC) in the air, being expressed in a second
point (A) of the aircraft (AC);auxiliary means (7) for calculating a
corrective term being representative of an apparent wind; andthird means
(4) for determining, at least from said first and second speed
information, said wind characteristic in the terrestrial reference
system, said third means (4) being formed so as to determine said wind
characteristic taking into account said corrective term,wherein said
auxiliary means (7) comprise elements for calculating said corrective
term TC using the following expression:TC={right arrow over (Ω)}
{right arrow over (GA)}wherein: represents the vector product;{right
arrow over (Ω)} represents the rotation rate of the aircraft (AC)
in an inertial reference system;G represents a reference point of the
aircraft (AC), corresponding to said first point; andA represents the
position on the aircraft (AC) of at least one anemometric probe, the
measurements thereof being used for determining said second piece of
speed information, such a position A corresponding to said second point.

5. A system for automatically generating aboard an aircraft (AC) at least
one wind characteristic existing outside said aircraft (AC),wherein it is
located aboard the aircraft (A) and comprises:means (13) for generating a
first piece of speed information;means (11) for generating a second piece
of speed information; anda device (1) according to claim 4, for
estimating said wind characteristic by means of said first and second
speed information.

6. A system according to claim 5, it further comprising means (15) so as
to show to a crew member of the aircraft (AC) the wind characteristic
having been estimated by said device (1).

7. An aircraft, comprising a device (1) according to claim 4.

8. An aircraft, comprising a system (10) according to claim 5.

Description:

[0001]The present invention relates to a method and a device for
estimating on an aircraft at least one wind characteristic existing
outside said aircraft.

[0002]It is known that it is desirable, in particular in the approaching
and landing phases, to be able to estimate, aboard an aircraft, in
particular a transport aircraft, the force and the direction of the wind,
i.e., the speed and the moving direction, with respect to the ground, of
the air mass in which the aircraft moves.

[0003]Such speed and wind direction information could be more particularly
used: [0004]for managing the aircraft navigation (flight plan); and
[0005]for assisting steering, in particular upon approaching a landing
runway and the subsequent landing.

[0006]Such a wind estimation is generally achieved through the aircraft
speed with respect to the ground, being, for example, determined by means
of on-board inertia units, and the aircraft speed in the air, being, for
example, measured by means of pressure probes, also on board.

[0007]However, such a usual estimating method often leads to erroneous
results, more particularly due to a possible mismatch between the results
as obtained from two redundant ways generally provided on aircrafts. It
is known, from FR-2 906 615, a wind estimating device which allows to
perform, aboard an aircraft, an accurate estimation of the wind. To this
end, such a usual device uses, in addition to the above mentioned speed
information, a piece of information relating to the attack of the
aircraft in the air, for calculating the horizontal component of the wind
(force and direction). Taking into account the attack, i.e., the moving
slope of the aircraft in the air, in addition to such a move speed,
allows for a more accurate estimation of the wind to be reached. Such an
estimation of the wind could be further refined through taking into
account an additional piece of information being representative of the
measured slide slip.

[0008]In such usual estimations, the speed of the wind is calculated from
the difference between the ground speed of the aircraft and the speed of
the aircraft in the air. Such a calculation is exact, when the
measurements of the ground and air speeds are expressed in one single
point of the aircraft. Now, this is not generally the case. In fact:
[0009]the ground speed of the aircraft is generally expressed (i.e.
defined) at the centre (gravity centre or reference centre) of the
aircraft; whereas [0010]the air speed and the slide slip and attack
angles are obtained from measurements achieved by common probes being
generally located at the level of the front tip of the aircraft, where
the air flow is the least turbulent.

[0011]Consequently, due to the use of data as obtained from the
measurements achieved at two different points of the aircraft, the usual
estimations of the wind show some inaccuracy, as soon as the aircraft
performs rotation operations. The usual estimations are thus only
accurate when the aircraft is flying along a straight line. Such an
important drawback restricts the cases of use for the wind speed
estimated by the common devices.

[0012]Additionally, in the usual solutions, estimating in general occurs
only in two dimensions in the horizontal plane, i.e. in the plane being
normal to the surface of the earth. This also contributes to limit the
cases of use for the estimated wind speed.

[0013]The present invention aims at overcoming such drawbacks. It relates
to a method for performing, on an aircraft, a particularly accurate
estimation of at least one characteristic (speed, direction) of the wind
existing inside said aircraft, and this, whatever the operation (straight
line flight or rotational flight) performed by the aircraft at the time
when measurements adapted for such an estimation are being performed.

[0014]To this end, according to the invention, said method wherein, upon a
flight of said aircraft, the following automated operations are
performed: [0015]a) a first piece of speed information is received
relating to the speed of the aircraft in a terrestrial reference system,
being expressed in a first point (in particular, the gravity centre) of
the aircraft; [0016]b) a second piece of speed information is received
relating to the speed of the aircraft in the air, being expressed in a
second point (located, for instance, at the level of the nose) of the
aircraft; and [0017]c) said wind characteristic is determined in said
terrestrial reference system, from said first and second pieces of speed
information,is noteworthy in that, in addition, a corrective term is
determined being representative of an apparent wind created upon a
rotation of the aircraft and in that in step a), said wind characteristic
is determined taking into account said corrective term.

[0018]Thus, according to this invention, said corrective term is
integrated into the calculation of the wind characteristics, enabling to
eliminate the apparent wind being introduced into the calculations when
anemometric operations are performed upon a rotational motion of the
aircraft and the speed information being used in such calculations is
expressed in two different points of the aircraft. Such an apparent wind
introduced in the usual estimations, an error in the calculation of said
wind characteristic, such error being thus corrected by means of this
invention.

[0019]Consequently, the method according to the invention provides a
particularly accurate and reliable estimation of at least one wind
characteristic, more particularly, the speed and/or direction thereof,
and this whatever the type of flight operation (straight line flight or
rotational flight) performed by the aircraft upon measurements provided
for the calculation.

[0020]In a preferred embodiment, said corrective term TC is calculated
using the following expression:

TC={right arrow over (Ω)} {right arrow over (GA)}

wherein: [0021] A represents the vector product; [0022]{right arrow
over (Ω)} represents the rotation rate of the aircraft in an
inertial reference system; [0023]G represents a reference point of the
aircraft, corresponding to said first point; and [0024]A represents the
position on the aircraft of at least one anemometric probe, having its
measurements used for determining said second piece of speed information,
such a position A corresponding to said second point.

[0025]In such preferred embodiment, advantageously, there is calculated in
step c), as the wind characteristic, a speed vector {right arrow over
(Vv)} of said wind, using the following expression:

wherein, in addition to the above mentioned parameters: [0026]{right
arrow over (Vgs)} represents said first piece of speed information
relating to the speed of the aircraft in a terrestrial reference system;
and [0027]{right arrow over (Vair)} represents said second piece of speed
information relating to the speed of the aircraft in the air.

[0028]Thus, through this invention, the wind is calculated under the form
of a vector {right arrow over (Vv)}, i.e. in three dimensions. Thereby,
there is available, as opposed to the usual estimations, in addition to
the wind speed in the horizontal plane, also the vertical component of
said wind speed. This enables to increase the cases of use for such wind
estimation.

[0029]The present invention also relates to a method for automatically
implementing aboard an aircraft at least one wind characteristic existing
outside said aircraft.

[0030]This method is noteworthy in that, upon a flight of said aircraft,
the following automated operations are automatically performed:
[0031]a) a first piece of speed information is determined on the aircraft
relating to said speed of the aircraft in a terrestrial reference system;
[0032]b) a second piece of speed information is determined on the
aircraft relating to the speed of the aircraft in the air; and [0033]c)
said wind characteristic is determined by means of said first and second
speed information, implementing the above mentioned method.

[0034]In addition, the present invention relates to a device for
automatically estimating aboard an aircraft at least one wind
characteristic existing outside said aircraft, said method being aboard
the aircraft and comprising: [0035]first means for receiving a first
piece of speed information relating to the speed of the aircraft in a
terrestrial reference system, being expressed in a first point of the
aircraft; [0036]second means for receiving a second piece of speed
information relating to the speed of the aircraft in the air, being
expressed in a second point of the aircraft; and [0037]third means for
determining, at least from said first and second speed information, said
wind characteristic in the terrestrial reference system.

[0038]According to this invention, said device is noteworthy in that:
[0039]it further comprises auxiliary means for determining a corrective
term being representative of an apparent wind created upon a rotation of
the aircraft; and [0040]said third means are formed so as to determine
said wind characteristic taking into account said corrective term
determined by said auxiliary means.

[0041]The device according to this invention thus enable to achieve an
accurate and reliable estimation of at least one characteristic (wind,
direction) of the wind existing outside the aircraft, and this, whatever
the operation (straight line flight or rotational flight) being performed
by the aircraft when measurements are performed for such an estimation.

[0042]In addition, the present invention further relates to: [0043]a
system comprising, in addition to a device, such as the above mentioned
one: [0044]means for generating said first piece of speed information;
[0045]means for generating said second piece of speed information; and/or
[0046]an aircraft, more particularly, a transport aircraft, comprising
a device and/or a system such as the above mentioned ones.

[0047]The figures of the appended drawing will make it obvious how to
implement this invention. On these figures, identical numerical
references indicate identical elements.

[0048]FIG. 1 is the block diagram of a system according to the invention
for automatically estimating from an aircraft a wind characteristic.

[0049]FIG. 2 is a schematic view of an aircraft, to which the present
invention is applied.

[0050]FIGS. 3 and 4 are two diagrams illustrating the reference points to
be used in the calculations as implemented within the scope of the
present invention.

[0051]The device 1 according to the invention and schematically
represented on FIG. 1 is adapted for estimating aboard an aircraft AC,
more particularly, a transport aircraft, at least one characteristic or
component (as hereinafter set forth) of the wind being generated outside
said aircraft AC, i.e. that such a device 1 is intended for estimating at
least one component of a motion of an air mass relative to a terrestrial
reference system, from the aircraft AC moving in such an air mass.

[0052]To this end, said device 1 being aboard the aircraft AC, comprises:
[0053]means 2 for receiving a first piece of speed information relating
to the speed of the aircraft AC in a terrestrial reference system. Such a
speed is expressed in a first point G of the aircraft AC; [0054]means 3
for receiving a second piece of speed information relating to the speed
of the aircraft AC in the air. Such a speed is expressed in a second
point A of the aircraft AC; and [0055]means 4 being linked via links 5
and 6 to said means 2 and 3 and being formed so as to determine, at least
from said first and second speed information as received from said means
2 and 3, said wind characteristic in said terrestrial reference system.

[0056]According to the invention, in particular in order to obtain a
particularly accurate and reliable estimation of said wind
characteristic, and this whatever the motions or the operations of the
aircraft AC: [0057]the device 1 further comprises auxiliary means 7 for
determining a corrective term TC, as hereinafter set forth, being
representative of an apparent wind created upon a rotation of the
aircraft AC; and [0058]said means 4 are linked via a link 8 to said means
7 and are formed so as to determine said wind characteristic taking into
account the corrective term TC as determined by said means 7.

[0059]The device 1 according to the invention is part of a system 10 for
automatically generating aboard an aircraft AC at least one wind
characteristic existing outside said aircraft AC. Such a system 10
comprises, in addition to said device 1, more particularly: [0060]means
11 being linked via a link 12 to said device 1 and being formed so as to
generate said second piece of speed information, as mentioned
hereinafter; and [0061]means 13 being linked via a link 14 to said device
1 and being formed so as to generate said first piece of speed
information, as set forth hereinafter.

[0062]Said system 10 further comprises means 15 being linked via a link 16
to said device 1 and being formed so as to show to a crew member of the
aircraft AC, more specifically to the pilot, the wind characteristic(s)
having been estimated by said device. To this end, said means 15 could
more specifically show such data on a viewing screen 17 in the cockpit of
the aircraft AC.

[0063]Thus, through the invention, said corrective term TC is integrated
into the wind characteristic, enabling to eliminate the apparent wind
being introduced into the calculations when the anemometric measurements
are achieved upon the rotation of the aircraft AC and the speed
information being used in the calculations are expressed in two different
points A and G of the aircraft AC. Within the scope of the present
invention, a piece of speed information being expressed in a point A, G
means that it has either been calculated with respect to this point, or
that measurements to be used for calculating it were achieved at the
point.

[0064]Such an apparent wind introduced, in the common estimations, an
error in the calculation of said wind characteristic, such an error being
thus corrected according to the invention. Consequently, the device 1 (or
system 10) according to this invention provides a particularly accurate
and reliable estimation of at least one wind characteristic, more
particularly the speed and/or direction thereof, and this, whatever the
type of flight operation (straight line flight or rotational flight)
being performed by the aircraft AC when the measurements intended for the
calculation are being achieved.

[0065]In a preferred embodiment, said means 7 calculate said corrective
term TC using the following expression:

TC={right arrow over (Ω)} {right arrow over (GA)}

wherein: [0066] represents the vector product; [0067]{right arrow over
(Ω)} represents the rotation rate of the aircraft AC in an inertial
reference system; [0068]G represents a reference point of the aircraft
AC, in particular the gravity center thereof, corresponding to said first
mentioned point; and [0069]A represents the position on the aircraft AC
of at least one anemometric probe, having its measurements being used for
determining said second piece of speed information. Such a position A
represented on FIG. 2 corresponds to said second mentioned point.

[0070]In this preferred embodiment, said means 4 calculate, as a wind
characteristic, a speed vector {right arrow over (Vv)} of said wind,
using the following expression:

wherein: [0071]{right arrow over (Vgs)} represents said first piece of
speed information; and [0072]{right arrow over (Vair)} represents said
second piece of speed information.

[0073]Estimating the speed of the wind is thus based on three terms,
namely: [0074]the speed {right arrow over (Vgs)} of the aircraft AC
with respect to the earth surface; [0075]the speed {right arrow over
(Vair)} of the aircraft AC in the air; and [0076]said corrective term TC
representing a wind created upon rotation of the aircraft AC. Taking into
account such a corrective term TC enables to eliminate the apparent wind
created on the anemometric probes upon the rotation of the aircraft AC.

[0077]In a particular embodiment, said means 11 comprise a set 18 of usual
anemometric sensors, being able to deliver information relating to the
motion of the aircraft AC in the air mass it is crossing at a given time.
Such anemometric sensors comprise, for example, a static pressure probe
and a total pressure probe, from which the air speed TAS (True Air
Speed), an angle of attack probe and a slide slip angle probe. It is to
be reminded that the air speed is the standard (or module) of the moving
(or speed) vector of the aircraft AC in the air mass. Information
delivered by such anemometric sensors could be processed within an
anemometric unit 19 being linked via a link 20 to said set 18, being
sometimes referred to as ADR (Air Data Reference) and usually generating,
more specifically, an piece of air speed information TAS (corresponding
to the standard of the vector TAS expressing the speed of the aircraft AC
in the air mass), an angle of attack α and a slide slip angle
β.

[0078]Moreover, in a particular embodiment, said means 13 could include
means 21 comprising: [0079]a set of inertia sensors allowing to
determine the motion of the aircraft AC with respect to the terrestrial
reference system. Such sensors comprise, for instance, three gyrometers
and three accelerometers; and [0080]a satellite positioning system [for
example of the GPS type (Global Positioning System)] able to deliver
information about the geographical location of the aircraft AC, based on
data received from orbiting satellites around the earth globe.

[0081]A processing unit 22 for the terrestrial reference (or inertia unit)
receives (via a link 23) and processes the information as supplied by
means 21 (more specifically, information issued, on the one hand, from
the set of inertia sensors and on the second hand, from the satellite
positioning system) and usually delivers, more specifically the ground
speed being the standard of the projection in the horizontal plane at the
place under consideration, of the speed vector {right arrow over (Vgs)}
of the aircraft AC with respect to the terrestrial reference system, as
well as the geographic course ψ, the pitching angle θ and the
rolling angle φ of the aircraft AC. Alternatively, the invention
could also be used in a system only comprising inertia sensors (or
alternatively, only the satellite positioning system) as a source of
positioning data. Means 21 (or the unit 22) further deliver some
information to the means 7 via a link 9.

[0082]It could be noticed that the anemometric unit 19 and the processing
unit 22 for the terrestrial reference could be gathered within a single
electronic housing, for instance, of the ADIRU (Air Data and Inertial
Reference Unit) type based on the ARINC 738 standard.

[0083]Additionally, although a single item of each element is represented
on FIG. 1, it is possible to multiply by two or three each of such
elements in order to obtain a redundant architecture.

[0084]It is to be noticed that the direction of the wind is equal to the
angle ψt between the axis directed to the North of the Earth and the
speed vector {right arrow over (Vv)} of the wind determined by the device
1. Such a wind direction is obtained using the following expression:

ψt=arc tg(VvEO/VvNS)

wherein:

[0085]VvEO is the component of the wind speed in the East-West direction
and VvNS is the component of the wind speed in the North-South direction.

[0086]The speed vector of the wind {right arrow over (Vv)} in a
terrestrial reference point could be written as follows:

Vv → = ( VvNS VvEO VvZO ) X →
0 Y → 0 Z → 0 ##EQU00001##

[0087]Hereinafter, the equations to be used in the usual reference points
will be set forth, using the common definitions of the angle used on the
aircraft AC, namely an aircraft reference point RA and a terrestrial
reference point RT.

[0088]The principle being described for a vector equation, it is
applicable whatever the projection reference system and the definition of
the angles of the aircraft AC being used.

[0089]More precisely, there are used, as represented on FIGS. 3 and 4:
[0090]an aircraft reference system Ref1 moving with the aircraft AC, i.e.
that each point of the aircraft AC is stationary in such a reference
system Ref1. Such a reference system Ref1 could be defined by: [0091]the
reference point G; and [0092]an aircraft reference point RA of axes X1,
Y1, Z1, wherein: [0093]X1 represents the longitudinal axis of the
aircraft AC, being defined as positive from the tail to the nose of the
aircraft AC; [0094]Y1 represents the axis perpendicular to the symmetry
plane of the aircraft AC, being defined as positive towards the right
wing; and [0095]Z1 is the axis completing the trihedron (comprised within
the symmetry plane of the aircraft AC); [0096]a terrestrial reference
system Ref0 moving with the Earth, that is that each point of the Earth
is stationary within such a reference system Ref0, more particularly, the
surface and the centre thereof. Such a terrestrial reference system Ref0
could be defined using a terrestrial reference point RT of axes X0, Y0,
Z0, wherein: [0097]X0 is a horizontal direction and positive towards the
North of the Earth; [0098]Y0 is a horizontal direction and positive to
the West; and [0099]Z0 completes the trihedron (and points towards the
centre of the Earth); and [0100]an inertial or Galilean reference
system Refa, representing the measurement reference of the inertia
sensors (gyroscopes and accelerometers) of the aircraft AC. It could be
defined by: [0101]the centre of the Earth; and [0102]three inertial
directions (pointing, for example, towards particular stars).

[0103]An aerodynamic reference point Ra could also be considered of axes
Xa, Ya and Za, wherein: [0104]Xa represents the axis and the
orientation of the air speed; [0105]Ya is defined in the same plane as Xa
and Y1; and [0106]Za completes the trihedron (and is included within the
symmetry plane of the aircraft AC).

[0114]The position of the aircraft A is localized in the terrestrial
reference point RT by all three angles θ, φ and ψ, as
represented on FIG. 3 (showing the aircraft reference point RA in the
terrestrial reference point RT), and the direction of the air speed
{right arrow over (Vair)} is localized in the aircraft reference RA by
both angles α and β, as represented on FIG. 4 (showing the air
speed in the aircraft reference point RA).

[0115]The following coordinates are obtained of the different vectors in
the above mentioned reference points: [0116]the speed of the wind in
the terrestrial reference system. Such a vector is expressed in the
aircraft reference point RA:

[0118] V → air = ( TAS 0 0 ) X
→ a Y → a Z → a
##EQU00005## [0119]the rotation rate of the aircraft AC in the
inertial reference system (measurement of gyroscopes of the aircraft A).
Such a vector is expressed in the aircraft reference point RA:

[0130]Herein below, the calculation principle to be used is justified.

[0131]It is known that the value of the wind speed in the terrestrial
reference system Ref0 is defined by:

V → v = ( CA → t ) Ref 0
##EQU00009##

with: [0132]C, the centre of the Earth (stationary point of reference in
the inertial reference system Refa and the terrestrial reference system
Ref0); and [0133]A, the place where the anemometric probes or sensors are
located measuring the air mass.

[0134]The vector is split in two parts so as to have the speed of the
aircraft AC appear in the terrestrial reference system Ref0: or:

[0135]But the air speed is measured in the aircraft reference system Ref1.
The usual formula of drift reference system change is applied:

( GA → t ) Ref 0 = ( GA →
t ) Ref 1 + Ω → 1 GA →
##EQU00011##

with: [0136]G, the reference point of the aircraft AC; [0137]A, the
position of the anemometric probes;

[0137] V → air = - ( GA → t ) ,
##EQU00012## the air speed in the aircraft reference system Ref1; and
[0138]{right arrow over (Ω)}1 the rotation rate of the aircraft
reference system Ref1 in the terrestrial reference system Ref0.

[0139]At such a time, it is approximated that the terrestrial reference
system Ref0 is Galilean. This allows for the measurement of the
gyroscopes to be directly used for calculating the vector illustrating
the rotation rate. Such an approximation ({right arrow over
(Ω)}1={right arrow over (Ω)}) is possible for the present
application, as the rotation of the Earth is very slow and the lever arm
is reduced, so that the inaccuracy being introduced is minor (lower than
a 1/100th of knot).

[0140]Thus, finally, the following expression is obtained (being used by
the means 4 of the device 1):

[0141]The present invention thus takes into account the following
parameters: [0142]the motion speed of the aircraft AC in the
terrestrial reference point RT; [0143]the speed of the aircraft AC in the
air; [0144]the direction of the speed of the aircraft AC in the air
(angle of attack and slide slip angle); and [0145]the inertia angular
speed.

[0146]However, implementing the present invention neither depends on the
sensors to be used, nor on the calculation methods to be used for
determining such different parameters.